# How to draw a number line in Latex with math notation in each position?

First of all, this is a great site it's taught me so much about latex and hopefully I can also learn how to draw diagrams.

The diagram is from a youtube video explaining complex numbers:

I imagine the code looks something like this:

\documentclass[11pt]{article} %allowed 12pt
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{tikz}
\usetikzlibrary{arrows}

\begin{document}

%text explaining the diagram goes here

\begin{tikzpicture}
%\begin{centre}
\draw[latex-latex] (-4.5,0) -- (4.5,0) ; %edit here for the axis
\foreach \x in  {-4,-3,-2,-1,0,1,2,3,4} % edit here for the number on vertical lines
\draw[shift={(\x,0)},color=black] (0pt,3pt) -- (0pt,-3pt);%mooves top daches, (left tilt, up hight)---(right tilte, down hight)

%up arrow for \sqrt {-1}\in \mathbb{C}
\foreach \x in {-\infty \in \mathbb{Z} ,,-\sqrt {2}\in \mathbb{R},-\dfrac {1} {1}\in \mathbb{Q} ,0,1\in \mathbb{N},\dfrac {2} {4}\in \mathbb{Q},\pi\in\mathbb{R} ,\infty \in \mathbb{Z} } % edit here for the numbers at each position
%down arrow for -\sqrt {-1}\in \mathbb{C}

\draw[shift={(\x,0)},color=black] (0pt,0pt) -- (0pt,-3pt) node[below]{$\x$};%mooves botom dashes
%\end{centre}

\end{tikzpicture}

%text after the diagram goes here

\end{document}


Thanks for the help, I've tried looking into the pgfmanual, but can't seem to find an example to follow.

Are you looking for something like this? Below I provide raw coding (i.e. I do not use cycles or anything like that). I don't understand if you want just that drawing or a macro to draw any picture you want in that style.

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}[xscale = 1.5]

% draw axis
\draw [thick, ->] (0,0.25) -- (0,2.2);
\draw [thick, ->] (0,-0.65) -- (0,-2.2);
\draw [thick, <->] (-4.5,0) -- (4.5,0);

% draw lines in x axis
\draw (0,-0.2) -- (0,0.2); % zero
\draw (0.5,-0.2) -- (0.5,0.2); % 2/4 \in \mathbb{Q}
\draw (1.3,-0.2) -- (1.3,0.2); % 1 \in \mathbb{N}
\draw (-1,-0.2) -- (-1,0.2); % -1/1 \in \mathbb{Q}
\draw (3.14159265359,-0.2) -- (3.14159265359,0.2); % \pi \in \mathbb{R}
\draw (4,-0.2) -- (4,0.2);
\draw (-4,-0.2) -- (-4,0.2);
\draw (-2,-0.2) -- (-2,0.2); %-\sqrt(2) \in \mathbb{R}

% write math symbols
\node [below] at (0,-0.2) {$0$};
\node [below] at (0.5,-0.2) {$\frac{2}{4}\in\mathbb{Q}$};
\node [below] at (1.3,-0.2) {$1\in\mathbb{N}$};
\node [below] at (-1,-0.2) {$-\frac{1}{1}\in\mathbb{Q}$};
\node [below] at (3.14159265359,-0.2) {$\pi\in\mathbb{R}$};
\node [below] at (-2,-0.2) {$-\sqrt{2}\in\mathbb{R}$};
\node [above] at (4,0.2) {$\infty$};
\node [above] at (-4,0.2) {$-\infty$};
\node [right] at (0,1.5) {$\sqrt{-1} \in \mathbb{C}$};
\node [left] at (0,-1.5) {$-\sqrt{-1} \in \mathbb{C}$};

\end{tikzpicture}

\end{document}

• Just the exact drawing is fine because I learn just by playing around with the code. What are cycles and how would it improve this code. If you have some resource/macro to learn how to do any picture in that style would be fantastic. Then maybe I'll be able to learn how to make the lines a bit more bold and make it look like the hand drawn version. – UniStuffz Jan 12 '17 at 8:56
• I'm not that versed in TikZ, sadly. I have yet to read the manual, which I link here: ctan.org/pkg/pgf – Ignacio Correa Jan 12 '17 at 13:39